A display device having a non-self-emissive display panel such as a translucent liquid crystal display panel generally has such a configuration that a light source device for a display device that includes a light source is disposed on the back side of the display panel. The light source device includes the light source and a given number of sheet-shaped or film-shaped optical members of given type that are arranged to control the properties of light the light source emits. The light source device projects the light the properties of which have been controlled by the optical members toward the back side of the display panel. The light projected toward the back side of the display panel is transmitted through the display panel, making an image displayed visible on the front side of the display panel.
Examples of the sheet-shaped or film-shaped optical members include a diffusion sheet having a function of diffusing light and a lens sheet having a light gathering function. In order to support the sheet-shaped or film-shaped optical members, a given number of through holes are disposed adjacent to upper sides of the sheet-shaped or film-shaped optical members in a normal usage state, convex hooks are disposed adjacent to an upper side of a chassis of the light source device, and the hooks are fit in the through holes of the sheet-shaped or film-shaped optical members so as to hang the sheet-shaped or film-shaped optical members on the hooks. In particular, a plurality of through holes are provided to the sheet-shaped or film-shaped optical members, a plurality of hooks are provided to the chassis of the light source device, and bosses of the hooks are fit in the through holes so as to hang the sheet-shaped or film-shaped optical members (in other words, the sheet-shaped or film-shaped optical members are hung on the plurality of hooks).
If wrinkle or warpage occurs in the sheet-shaped or film-shaped optical members, the wrinkle or warpage causes irregular brightness or shadow on the front side (screen) of the display panel. The irregular brightness or shadow could decrease display quality of the display device. Accordingly, it is preferable to keep the sheet-shaped or film-shaped optical members with no wrinkle or warpage.
In the configuration that the plurality of through holes are disposed adjacent to the upper sides of the sheet-shaped or film-shaped optical members in the normal usage state and the bosses are fit in the through holes so as to hang the sheet-shaped or film-shaped optical members, the weight of the sheet-shaped or film-shaped optical members is dispersed to the peripheral portions of the plurality of through holes. Thus, occurrence of wrinkle or warpage in the sheet-shaped or film-shaped optical members can be prevented or minimized.
However, this configuration may cause the following problem. The vertical positions of the through holes that are disposed adjacent to the upper sides of the sheet-shaped or film-shaped optical members in the normal usage state are not always precisely aligned. In addition, the vertical positions of the hooks protruding from the chassis of the light source device are not always aligned. Thus, there is a possibility that some of the hooks come into contact with the inner surfaces of the corresponding through holes, so that the weight of the sheet-shaped or film-shaped optical members is put on the peripheral portions of those through holes, and the other hooks do not come into contact with the inner surfaces of the corresponding through holes, so that the weight of the sheet-shaped or film-shaped optical members is not put on the peripheral portions of those through holes. In such a case, the weight of the sheet-shaped or film-shaped optical members is concentrated on the peripheral portions of the through holes that come into contact with the hooks, and wrinkle or warpage could occur in the sheet-shaped or film-shaped optical members.
In view of this, in the configuration that the plurality of through holes are provided to the sheet-shaped or film-shaped optical members and the plurality of hooks protruding from the chassis are disposed adjacent to the upper side of the chassis, the vertical positions of the plurality of through holes in the sheet-shaped or film-shaped optical members and the vertical positions of the plurality of hooks protruding from the chassis should be precisely aligned. However, it is actually difficult to precisely align the vertical positions of the plurality of through holes in the sheet-shaped or film-shaped optical members and the vertical positions of the plurality of hooks protruding from the chassis.